Chronic kidney disease (CKD) is increasing worldwide and is emerging as a major global health threat.[1] Accurately assessing and monitoring renal function is of critical importance in patients with CKD. Currently, kidney injury is clinically tested by serum creatinine, serum cystatin-C, or urine protein or albumin. These are markers that measure kidney functional loss, but not kidney cellular injury. A few urine proteins are also measured as markers of tubulointerstitial injury, but they are either not generally used clinically (e.g., N-acetyl-beta-D-glucosaminidase) or are experimental tests (NGAL, KIM1, Interleukin-18 (IL-18)).
Periostin was initially identified in osteoblasts and acts as an adhesion molecule during bone formation, supports osteoblastic cell line attachment, and is involved in cell survival, proliferation, migration, and differentiation.[3-6] It is induced in processes and pathologies including cardiac embryogenesis, adult cardiac disease, metastatic disease, and tumor suppression.[7] Evidence in these tissues suggests that periostin may play a fundamental role in tissue remodeling [8,9], and in disease of the cardiovascular system.[10-12] Periostin is induced in the kidney during nephrogenesis, but it is not observed in adult kidney under normal conditions.[13] It also may accelerate cyst growth and promote interstitial remodeling in polycystic kidney disease (PKD).[14]